1. Field of the Invention
The present invention relates generally to image authentication, and more particularly to a method and apparatus in a camera for non-destructively marking an image, and creating image authentication data in the process of image acquisition.
2. Brief Description of the Prior Art
The prevention of unauthorized use, and the related problem of authentication of documents and images is a problem that has been addressed in the past. In the area of unauthorized use, photographers need to display their images for potential sale in a condition that discourages use of the image prior to an agreement. Examples include stock-photography and image banks. In an attempt to prevent unauthorized use, a photographer may apply a mark (typically termed a "watermark") on a copy of the image to discourage its use. Even so, there is always the risk that someone may come in possession of the original. A particular problem exists in the field of digital photography where the concept of an "original" photograph is highly questionable, due to the capability of image modification.
In the area of authentication, a reliable money supply requires a method of authenticating the currency. Signatures on numerous types of documents require authentication, the efforts ranging from the use of a notary public for official documents to the showing of a driver's license to a store clerk. Picture identification is used in many areas, but generally lacks any means of assuring that the picture is in fact the person otherwise identified, for example on a driver's license or security badge/card. The problem with a picture I.D. is one of assuring that the picture on the card is the original. With no method of checking the image authenticity, false identifications can be produced by changing the image after the original picture is taken. A particular problem exists with modern digital photography which provides a user extensive and easy flexibility in modifying images through pixel manipulation, thus reiterating the problem previously cited concerning what is to be considered an original versus a modified or manipulated image. One method of authenticating an image is through physically marking an image in a manner that is very difficult to reproduce, such as an image that can only be viewed at a certain angle, as described in U.S. Pat. No. 5,468,581 by Coe, et al. U.S. Pat. No. 5,410,642 by Hakamatsuka et al. describes a method of manufacturing an I.D. card with embossing over a photograph and applying a code to the I.D. card. U.S. Pat. No. 5,420,924 by Berson et al. describes extracting a portion of information from a digital image and placing it on one side of an I.D. card with the photo on the other. The photo can then by checked for subsequent alteration by decoding the data on the reverse side and displaying and overlaying the resulting image with the photo to visually display discrepancies.
The disadvantage of the above methods of authenticating images is that they involve adding authentication indicators to an image or image data that already exists in a viewable form. These methods are used to check for subsequent alterations of the image. The problem with these methods is that any amount of time could lapse between the creation of the original image and the inclusion of authentication data, and they therefore provide no way of assuring the authenticity of the presumed original. In other words, there is no guarantee that the original image was not manipulated before the authentication marking was installed. Similarly, in the situation where a visible mark is placed on an image to discourage unauthorized use, existing methods that apply a mark to a copy for display run the risk that someone may obtain possession of the original.
There is clearly a great need for a method and apparatus for marking an image and creating authentication data at the time of acquisition of the image, by-passing the need to first create and store a viewable original that could be intercepted by unauthorized persons.